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Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous.

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Presentation on theme: "Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous."— Presentation transcript:

1 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Olfa Nasraoui Knowledge Discovery & Web Mining Lab Dept of Computer Engineering & Computer Sciences University of Louisville E-mail: olfa.nasraoui@louisville.edu URL: http://www.louisville.edu/~o0nasr01 Supported by US National Science Foundation Career Award IIS-0133948

2 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Compressed Vita Endowed Chair of E-commerce in the Department of Computer Engineering & Computer Science at the University of Louisville Director of the Knowledge Discovery and Web Mining Lab at the University of Louisville. Research activities include Data Mining, Web mining, Web Personalization, and Computational Intelligence (Applications of evolutionary computation and fuzzy set theory). Served as program co-chair for several conferences & workshops, including WebKDD 2004, 2005, and 2006 workshops on Web Mining and Web Usage Analysis, held in conjunction with ACM SIGKDD International Conferences on Knowledge Discovery and Data Mining (KDD). Recipient of US National Science Foundation CAREER Award. What I will speak about today is mainly the research products and lessons from a 5-year US National Science Foundation project

3 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments My Collaborative Network?

4 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Team: Knowledge Discovery & Web Mining Lab University of Louisville Director: Olfa Nasraoui (speaker) Current Student Researchers (alphabetically listed): Jeff Cerwinske, Nurcan Durak, Carlos Rojas, Esin Saka, Zhiyong Zhang, Leyla Zhuhadar Note: Gender balanced & multicultural ;-)

5 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Past and Present Collaborators Raghu Krishnapuram, IBM Research Anupam Joshi, University of Maryland, Baltimore County Hichem Frigui, University of Louisville Hyoil Han, Drexel University Antonio Badia, University of Louisville Roberta Johnson, University Corporation for Atmospheric Research (UCAR) Fabio Gonzalez, Nacional University of Colombia Cesar Cardona, Magnify, Inc. Elizabeth Leon, Nacional University of Colombia Jonatan Gomez, Nacional University of Colombia

6 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Introduction Information overload: too much information to sift/browse through in order to find desired information –Most information on Web is actually irrelevant to a particular user This is what motivated interest in techniques for Web personalization As they surf a website, users leave a wealth of historic data about what pages they have viewed, choices they have made, etc Web Usage Mining: A branch of Web Mining (itself a branch of data mining) that aims to discover interesting patterns from Web usage data (typically Web Log data/clickstreams) (Yan et al. 1996, Cooley et al. 1997, Shahabi, 1997; Zaiane et al. 1998, Spiliopoulou & Faulstich, 1999, Nasraoui et al. 1999, Borges & Levene, 1999, Srivastava et al. 2000, Mobasher et al. 2000; Eirinaki & Vazirgiannis, 2003)

7 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Introduction Web Personalization: Aims to adapt the Website according to the users activity or interests (Perkowitz & Etzioni, 1997, Breeze et al. 1998, Pazzani, 1999, Schafer et al. 1999, Mulvenna, 2000; Mobasher et al. 2001, Burke. 2002, Joachims, 2002; Adomavicius &. Tuzhilin, 2005) Intelligent Web Personalization: often relies on Web Usage Mining (for user modeling) Recommender Systems: recommend items of interest to the users depending on their interest (Adomavicius & Tuzhilin, 2005) –Content-based filtering: recommend items similar to the items liked by current user (Balabanovic & Shoham, 1997) No notion of community of users (specialize only to one user) –Collaborative filtering: recommend items liked by similar users (Konstan et al., 1997; Sarwar et al., 1998; Schafer, 1999) Combine history of a community of users: explicit (ratings) or implicit (clickstreams) –Hybrids: combine above (and others) Focus of our research

8 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Some Challenges in WUM and Personalization Ambiguity: the level at which clicks are analyzed (URL A, B, or C as basic identifier) is very shallow, almost no meaning –Dynamic URLs: meaningless URLs even more ambiguity –Semantic Web Usage Mining: (Oberle et al., 2003) Scalability: Massive Web Log data that cannot fit in main memory requires techniques that are scalable (stream data mining) (Nasraoui et al.: WebKDD 2003, ICDM 2003) Handling Evolution: Usage data that changes with time –Mining & Validation in dynamic environments: largely unexplored area…except in: (Mitchell et al. 1994; Widmer, 1996; Maloof & Michalski, 2000) –In the Web usage domain: (Desikan & Srivastava, 2004; Nasraoui et al.: WebKDD 2003, ICDM 2003, KDD 2005, Computer Networks 2006, CIKM 2006) From Clicks to Concepts: few efforts exist based on laborious manual construction of concepts, website ontology or taxonomy –How to do this automatically? (Berendt et al., 2002; Oberle et al., 2003; Dai & Mobasher, 2002; Eirinaki et al., 2003) Implementing recommender systems can be slow, costly and a bottle neck especially –for researchers who need to perform tests on a variety of websites –For website owners that cannot afford expensive or complicated solutions

9 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Different Steps Of our Web Personalization System Recommendations Recommendation Engine Active Session Preprocessing Data Mining: Transaction Clustering Association Rule Discovery Pattern Discovery Site Files Server Logs User Sessions Post Processing / Derivation of User Profiles STEP 1: OFFLINE PROFILE DISCOVERY STEP 2: ACTIVE RECOMMENDATION User profiles/ User Model

10 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Challenges & Questions in Web Usage Mining Recommendations Recommendation Engine Active Session Preprocessing Data Mining: Transaction Clustering Association Rule Discovery Pattern Discovery Site Files Server Logs User Sessions Post Processing / Derivation of User Profiles STEP 1: OFFLINE PROFILE DISCOVERY ACTIVE RECOMMENDATION Dealing with Ambiguity: Semantics? Implicit taxonomy? (Nasraoui, Krishnapuram, Joshi. 1999) Website hierarchy (can help disambiguation, but limited) Explicit taxonomy? (Nasraoui, Soliman, Badia, 2005) From DB associated w/ dynamic URLs Content taxonomy or ontology (can help disambiguation, powerful) Concept hierarchy generalization / URL compression / concept abstraction: (Saka & Nasraoui, 2006) How does abstraction affect quality of user models? User profiles/ User Model

11 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Challenges & Questions in Web Usage Mining Recommendations Recommendation Engine Active Session Preprocessing Data Mining: Transaction Clustering Association Rule Discovery Pattern Discovery Site Files Server Logs User Sessions Post Processing / Derivation of User Profiles STEP 1: OFFLINE PROFILE DISCOVERY ACTIVE RECOMMENDATION User Profile Post-processing Criteria? (Saka & Nasraoui, 2006) Aggregated profiles (frequency average)? Robust profiles (discount noise data)? How do they really perform? How to validate? (Nasraoui & Goswami, SDM 2006) User profiles/ User Model

12 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Challenges & Questions in Web Usage Mining Recommendations Recommendation Engine Active Session Preprocessing Data Mining: Transaction Clustering Association Rule Discovery Pattern Discovery Site Files Server Logs User Sessions Post Processing / Derivation of User Profiles STEP 1: OFFLINE PROFILE DISCOVERY ACTIVE RECOMMENDATION Evolution: (Nasraoui, Cerwinske, Rojas, Gonzalez. CIKM 2006) Detecting & characterizing profile evolution & change? User profiles/ User Model

13 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Challenges & Questions in Web Personalization Recommendations Recommendation Engine Active Session Preprocessing Data Mining: Transaction Clustering Association Rule Discovery Pattern Discovery Site Files Server Logs User Sessions Post Processing / Derivation of User Profiles STEP 1: OFFLINE PROFILE DISCOVERY ACTIVE RECOMMENDATION In case of massive evolving data streams: Need stream data mining (Nasraoui et al. ICDM03, WebKDD 2003) Need stream-based recommender systems? (Nasraoui et al. CIKM 2006) How do stream-based recommender systems perform under evolution? How to validate above? (Nasraoui et al. CIKM 2006) User profiles/ User Model

14 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Challenges & Questions in Web Personalization Recommendations Recommendation Engine Active Session Preprocessing Data Mining: Transaction Clustering Association Rule Discovery Pattern Discovery Site Files Server Logs User Sessions Post Processing / Derivation of User Profiles STEP 1: OFFLINE PROFILE DISCOVERY ACTIVE RECOMMENDATION Implementing Recommender Systems: Fast, easy, scalable, cheap, free? At least to help support research… But Grand advantage: help the little guy… (Nasraoui, Zhang, Saka, SIGIR-OSIR 2006) User profiles/ User Model

15 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Whats in a click? Web Usage Mining: - Ambiguity: - Implicit Semantics: website hierarchy - Explicit Semantics: DB w/ taxonomy of dynamic URLs - What is effect of generalization / URL compression / concept abstraction - Noise: - Detecting and characterizing evolution in dynamic environments -Recommender Systems in dynamic environments - Fast, Easy, Free Implementation - Mining Conceptual Web Clickstreams Access log: Record of URLs accessed on Website Log entry: access date, time, IP address, URL viewed, …etc. Modeling User Sessions: set of clicks, pages, URLs ( Cooley et al. 1997) –Map URLs on site to indices –User session vector s(i): temporally compact sequence of Web accesses by a user (consecutive requests within time threshold: e.g. 45 minutes) URLs: –Orthogonal? (Traditional approach) –Exploit some implicit concept hierarchy: website hierarchy (easy to infer from URLs) (Nasraoui, Krishnapuram, Joshi. 1999) –Dynamic URLs: Exploit some explicit concept hierarchy: encoded in Web item database (Nasraoui, Soliman, Badia, 2005) How to take above into account? –Integrate into the similarity measure while clustering

16 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Similarity Measure (Nasraoui, Krishnapuram, Joshi. 1999) Map N U URLs on site to indices User session vector s (i) : temporally compact sequence of Web accesses by a user O. Nasraoui and R. Krishnapuram, and A. Joshi. Mining Web Access Logs Using a Relational Clustering Algorithm Based on a Robust Estimator, 8th International World Wide Web Conference, Toronto, pp. 40-41, 1999. If site structure ignored cosine similarity Taking site structure into account relate distinct URLs: p i : path from root to i th URLs node

17 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Web Session Similarity Measure: variant of cosine that takes into account item relatedness Taking site structure into account: Final Web Session Similarity = Concept Hierarchies: helpful in many data mining contexts: (E.g. in association rule mining: Srikant &. Agrawal, 1995, in text: Chakrabarti et al., 1997, in Web usage mining: Berendt, 2001, Eirinaki, 2003)

18 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Role of Similarity Measure: Adding semantics Problem: Dynamic URLs, such as universal.aspx?id=56: –hard to recognize based only on their URL affects presentation & interpretation of discovered user profiles! –hard to relate (among each other) based only on their URL affects Web usage mining! Solution: Use available external data that maps dynamic URLs to hierarchically related and more meaningful descriptions Explicit taxonomy: parent item child item transform URL into regular looking URL: parent/child/grand-child … etc handle this URL using previous implicit website hierarchy approach: inferred by tokenizing the URL string Ultimately, both implicit and explicit taxonomy information are seamlessly incorporated into the data mining algorithm (clustering) via the Web session similarity measure Web Usage Mining: - Ambiguity: - Implicit Semantics: website hierarchy - Explicit Semantics: DB w/ taxonomy of dynamic URLs - What is effect of generalization / URL compression / concept abstraction - Noise: - Detecting and characterizing evolution in dynamic environments - Recommender Systems in dynamic environments - Implementation - Mining Conceptual Web Clickstreams Olfa Nasraoui, Maha Soliman, and Antonio Badia, Mining Evolving User Profiles and More – A Real Life Case Study, In Proc. Data Mining meets Marketing workshop, New York, NY, 2005.

19 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Problem: Dynamic URLs, such as universal.aspx?id=56, are hard to recognize based only on their URL affects presentation of profiles! hard to relate (among each other) based only on their URL affects Web usage mining!. Solution: We resorted to available external data, provided by the website designers, that maps dynamic URLs to hierarchically related and more meaningful descriptions. menus_iditem_nameitem_levelparent_itemsequenceResource/url 56Regulations and Laws149391universal.aspx 4939NST Center®01Nst Example: Dynamic URL: universal.aspx?id=56 Semantic URL: NST Center® / Regulations and Laws Taxonomy Data Provided by the website designers Mapping Dynamic URLs to Semantic URLs (Nasraoui, Soliman, Badia, 2005)

20 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Mapping Dynamic URLs to Semantic URLs (another example) universal.aspx?id=6770 ? since item #6770 has as parent: item #56 menus_iditem_name item_ level parent_ itemsequenceurl 6770 Air Quality and Emission Standards2561universal.aspx Recall: Item 56 = (NST Center® / Regulations and Laws ) Hence, universal.aspx?id=6770 –NST Center® / Regulations and Laws / Air Quality and Emission Standards

21 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Concept Generalization/Abstraction Generalize lower/specific concepts to higher concepts Mechanism: –IF Sim (URL i, URL j ) > Threshold THEN merge URLs

22 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Concept Generalization/Abstraction Generalize lower/specific concepts to higher concepts Mechanism: –IF Sim (URL i, URL j ) > Threshold THEN merge URLs Effects: –Helps in disambiguation –URL compression Easily reach compression rates in 80% range depending on merging threshold

23 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Concept Generalization/Abstraction Generalize lower/specific concepts to higher concepts Mechanism: –IF Sim (URL i, URL j ) > Threshold THEN merge URLs –Effects: –Helps in disambiguation –URL compression Easily reach compression rates in 90% range depending on merging threshold

24 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Aggressive Concept Generalization/Abstraction Generalize even more lower/specific concepts to higher concepts Mechanism: –IF Sim (URL i, URL j ) > Even- bigger-Threshold THEN merge URLs More drastic effects: –Helps in disambiguation –URL compression Easily reach compression rates in 90% range depending on merging threshold

25 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Effect of Compression First, the mining + validation methodology: Perform Web Usage Mining: –Pre-process Web log data (includes URL transformations taking into account implicit or explicit concept hierarchy) –Cluster user sessions into optimal number of user profiles using HUNC (Hierarchical Unsupervised Niche Clustering) Localized Error-Tolerant profiles maximize a measure of soft transaction support with dynamically optimized error-tolerance –Optional Post-processing: (Later…) Frequency Averaging: compute frequency of each URL in each cluster profile Robust Profiles: ignore noisy user sessions when computing the above Validate discovered profiles against Web sessions Web Usage Mining: - Ambiguity: - Implicit Semantics: website hierarchy - Explicit Semantics: DB w/ taxonomy of dynamic URLs - What is effect of generalization / URL compression / concept abstraction - Noise: - Detecting and characterizing evolution in dynamic environments - Recommender Systems in dynamic environments - Implementation - Mining Conceptual Web Clickstreams σiσi

26 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Validation in an Information Retrieval Context (Nasraoui & Goswami, 2005) Profiles are patterns that summarize the input transaction data Quality of discovered profiles as a summary of the input transactions: –Precision (the profiles items are all correct or included in an original input transaction/session, i.e. no extra items) –Coverage/recall (a profiles items are complete compared to an transaction or session, i.e. no missed items) Interestingness measure: Given,define When Q ij = Cov ij, we call Q the Cumulative Coverage of Transactions, and it answers the Question –Is the data set completely summarized/represented by the mined profiles?. When Q ij = Prec ij, we call Q the Cumulative Precision of Transactions, and it answers the Question: –Is the data set faithfully/accurately summarized/represented by the mined profiles? These measures quantify the quality of mined profiles from the point of view of providing an accurate summary of the input data. Note: Q i = Probability {Precision Q min } or Probability {Coverage Q min }

27 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Precision Quality

28 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Coverage Quality

29 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Observations Compression decreases Quality (as expected …) However, level of compression (or abstraction) is not an important factor –What seemed to matter most is whether any compression is made or not? Compression distortion of original data (hence reduced quality) But lets not forget… Compression reduced sparsity of the session matrix (hence may help clustering results) Compression drastic reduction in # items (hence speed up the mining…)

30 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Handling Noise: Effect of Robustifying the Profiles (Nasraoui & Krishnapuram, SDM 2002) Perform Web Usage Mining: –Pre-process Web log data (includes URL transformations taking into account implicit or explicit concept hierarchy) –Cluster user sessions into optimal number of user profiles using HUNC (Hierarchical Unsupervised Niche Clustering) Localized Error-Tolerant profiles maximize a measure of soft transaction support with dynamically optimized error-tolerance –Post-process profiles: Simple Means: Compute (URL-frequency) means/centroids for each cluster Robust Means: –Robust weight of a session into a profile (varies between 0 and 1): »w ij = e(-(1-Sim ij ) 2 / i ) –user sessions with w ij < w min are ignored when averaging the URL frequencies in their cluster Validate discovered profiles against Web sessions Web Usage Mining: - Ambiguity: - Implicit Semantics: - Explicit Semantics: - What is effect of generalization / URL compression? - Noise: Effect of post- processing: - Robust profiles - Frequency averaging - Detecting and characterizing evolution in dynamic environments - Recommender Systems in dynamic environments - Recommender implementation - Mining Conceptual Web Clickstreams σiσi

31 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Precision Quality for various robustness levels w min No post- processing (raw profiles) Post- processing: various robustness levels

32 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Coverage Quality for various robustness levels w min No post- processing (raw profiles) Post- processing: Optimal robustness level (0.2)

33 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments F1 Quality for various robustness levels w min No post- processing (raw profiles)

34 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Observations Post-processing decreases Precision However, it improves coverage Computing the URL frequency means of all sessions in each profile/cluster brings up to the surface some URLs that did not make it through the optimization process resulting in the raw profiles –More URLs improve coverage, however, hurt precision

35 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Tracking Evolving Profiles (Nasraoui, Soliman, Badia, 2005) Mine user sessions in several batches (for each period) Automated comparison between new profiles and all the old profiles discovered in previous batches. Each profile p i is discovered along with an automatically determined measure of scale σ i boundary around each profile This allows us to automatically determine whether two profiles are compatible based on their distance compared to their respective boundaries Web Usage Mining: - Ambiguity: - Implicit Semantics: - Explicit Semantics: - What is effect of generalization / URL compression? - Noise: Effect of post-processing: - Robust profiles - Frequency averaging - Detecting and characterizing evolution in dynamic environments - Recommender Systems in dynamic environments - Recommender Implementation - Mining Conceptual Web Clickstreams σiσi σ2σ2 σ1σ1 p1p1 p2p2

36 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Four events can be detected from the comparison: –Persistence: New profiles are compatible with the old profiles. –Birth: New profiles are incompatible with any previous profile. –Death: Old profile finds no compatible profile from the new batch. –Atavism: Old profile that disappears, and then reappears (i.e. via compatibility) again in a later batch Tracking Evolving Access Patterns

37 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Profile Events time Profile 10 9 8 7 6 5 4 3 2 1 Atavism Persistence Birth Persistence Atavism time profile

38 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Tracking Evolving Access Patterns: Example of Atavism June 04July 04 /Write_Up_Display.A spx/Navy Community/Navy /ApprovedInterio rCoatings&Write _Ups_Id/BilgePr eservation /Write_Up_Display.A spx/Navy Community/Navy/Ap proved InteriorCoatings &Write_Ups_Id/B allast Tanks Aug 04- Part1 Aug 04-Part2 /Write_Up_Display.Aspx/ NavyCommunity/Nav y/Approved Interior Coatings&Write_Ups _Id/Bilge Preservation /Write_Up_Display.Aspx/ Write_Ups_Id/Project : MSC Non-Skid /Write_Up_Display.Aspx/ NavyCommunity/Nav y/Approval Of Coatings For Navy Use (Roadmap) Sep 04 Write_Up_Display.Asp x/NavyCommunity/ Navy/Approved Interior Coatings&Write_U ps_Id/Bilge Preservation /Write_Up_Display.Asp x/NavyCommunity/ Navy/Approved Exterior Coatings&Write_U ps_Id/Non-Skid Walk This profile reappears again in last 2 weeks of August The same profile disappears in first 2 weeks of August Here is one profile in June

39 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Why track Evolving Profiles? Form long term evolution patterns for interesting profiles –Predict seasonality –Support marketing efforts (if marketing campaigns are performed during these periods) –Forecast profile re-emergence to improve downstream personalization process via a caching process Frequent atavism profile should be cached Help improve scalability of Web usage mining algorithm –Process Web usage data in batches –Integrate tracking evolving profiles within mining algorithm –Maintain previously discovered profiles –Eliminate a majority of the new sessions from analysis (if similar to existing profiles) –Focus on typically smaller data consisting of sessions from truly emerging user profiles

40 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Recommender Systems in Dynamic Usage Environments For massive Data streams, must use a stream mining framework Furthermore must be able to continuously mine evolving data streams TECNO-Streams: Tracking Evolving Clusters in Noisy Streams –Inspired by the immune system –Immune system: interaction between external agents (antigens) and immune memory (B-cells) –Artificial immune system: Antigens = data stream B-cells = cluster/profile stream synopsis = evolving memory B-cells have an age (since their creation) Gradual forgetting of older B-cells B-cells compete to survive by cloning multiple copies of themselves Cloning is proportional to the B-cell stimulation B-cell stimulation: defined as density criterion of data around a profile (this is what is being optimized!) Web Usage Mining: - Ambiguity: - Implicit Semantics: - Explicit Semantics: - What is effect of generalization / URL compression? - Noise: Effect of post- processing: - Robust profiles - Frequency averaging - Detecting and characterizing evolution in dynamic environments - Recommender Systems in dynamic environments - Recommender Implementation - Mining Conceptual Web Clickstreams O. Nasraoui, C. Cardona, C. Rojas, and F. Gonzalez. Mining Evolving User Profiles in Noisy Web Clickstream Data with a Scalable Immune System Clustering Algorithm, in Proc. of WebKDD 2003, Washington DC, Aug. 2003, 71-81.

41 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments The Immune Network Memory External antigen (RED) stimulates binding B-cell B- cell (GREEN) clones copies of itself (PINK) Even after external antigen disappears: B-cells co- stimulate each other thus sustaining each other Memory! Stimulation breeds Survival

42 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments General Architecture of TECNO- Streams Approach 1-Pass Adaptive Immune Learning Evolving Immune Network (compressed into subnetworks) Evolving data Immune network information system Stimulation (competition & memory) Age (old vs. new) Outliers (based on activation) ?

43 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Initialize ImmuNet and MaxLimit Present NEW antigen data Update subNet* B-cells stimulations Clone and Mutate B-cells Trap Initial Data Compress ImmuNet Compress ImmuNet into K subNets Compute soft activations in subNet* Update subNet* B-cells Influence range /scale Identify nearest subNet* Kill lethal B-cells #B-cells > MaxLimit? Kill extra B-cells (based on age/stimulation strategy), increase acuteness of competition OR Move oldest patterns to aux. storage Memory Constraints No Start/ Reset Secondary storage Outlier? ImmuNet Stats & Visualization Activates ImmuNet? Clone antigen Yes No Yes Domain Knowledge Constraints

44 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Adherence to Requirements for Clustering Data Streams (Barbara 02) Compactness of representation –Network of B-cells: each cell can recognize several antigens –B-cells compressed into clusters/sub-networks Fast incremental processing of new data points –New antigen influences only activated sub-network –Activated cells updated incrementally –Proposed approach learns in 1 pass. Clear and fast identification of outliers –New antigen that does not activate any subnetwork is a potential outlier create new B-cell to recognize it –This new B-cell could grow into a subnetwork (if it is stimulated by a new trend) or die/move to disk (if outlier)

45 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Validation Methodology in Dynamic Environments Limit Working Capacity (memory) for Profile Synopsis in TECNO-Streams (or Instance Base for K-NN) to 30 cells/instances Perform 1 pass mining + validation –First present all combination subset(s) of a real ground-truth session to recommender, Determine closest neighborhood of profiles from TECNO-Streams synopsis (or instances for KNN) Accumulate URLs in neighborhood Sort and select top N URLs Recommendations –Then Validate against ground-truth/complete session (precision, coverage, F1), –Finally present complete session to TECNO-Streams (and K-NN)

46 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Validation Methodology in Dynamic Environments Scenario D (Drastic changes): –We partitioned real Web sessions into 20 distinct sets of sessions, each one assigned to one of 20 previously discovered and validated profiles. –Then we presented these sessions to the immune clustering + recommendation + validation algorithm one profile at a time. That is, we first present the sessions assigned to ground truth profile/trend 0, then the sessions assigned to profile 1, …, etc. Scenario M (Mild changes): present Web sessions in chronological order exactly as they were received in real time by the web server Scenario (Repeating Drastic changes): Same as Scenario D, but presented profiles 1,2,3,4,5,1,2,3,4,5 (Repetition).

47 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Dendogram of the 20 profile (vectors) 1.7K sessions, 343 URLs Memory capacity limited to 30 nodes in TECNO- Streams synopsis, 30 KNN-instances

48 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Drastic Changes: F1 versus session number (vertical lines: environment changes),1.7K sessions Ramp-up: both deteriorate equally as environment changes - With sustained environment, KNN climbs higher (intense memorization of immediate past) - On the other hand TECNO-Streams forms a compressed summary via optimization lossy compression

49 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Mild Changes: F1 versus session number, 1.7K sessions TECNO-Streams higher (noisy, naturally occurring but unexpected fluctuation call for more intelligent optimization?) The real challenge is that here, ALL 20 usage trends are presented simultaneously as opposed to one at a time (scenario M)!

50 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Repeating Drastic Changes: F1 versus session number (vertical lines: environment changes), 1.7K sessions KNN higher (same as drastic: intense memorization of immediate past) However, the 2 nd time that a past environment re-occurs: -TECNO-Streams performance improves significantly compared to the 1st time (longer term memory, 2 ndary immune response known to be stronger) - KNNs performance remains identical to the 1st time (deterministic)

51 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Dendogram of the 93 profile (vectors) Bigger Data Set (~ 30K sessions, 30K URLs):

52 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Memory capacity limited to 150 nodes in TECNO- Streams synopsis, 150 KNN-instances

53 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Bigger Data Set (~ 30K sessions, ~18K items): Drastic Changes: F1 versus session number (vertical lines: environment changes) Ramp-up: both deteriorate equally as environment changes Either one of KNN or TECNO-Streams seem to perform better depending on profile Overall, both recommenders performances are very poor for some usage trends!!! (Note the dimensionality and sparsity is much higher for the big data!) These trends are contaminated by too many noise sessions (close to 50%)!

54 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Bigger Data Set (~ 30K sessions): Mild Changes: F1 versus session number KNN-Streams slightly higher ?

55 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Bigger Data Set (~ 30K sessions): Repeating Drastic Changes: F1 versus session number (vertical lines: environment changes) KNN slightly higher (same as drastic: intense memorization of immediate past) However, the 2 nd time that a past environment re-occurs: -TECNO-Streams performance improves slightly compared to the 1st time (longer term memory, 2 ndary immune response known to be stronger) - KNNs performance remains identical to the 1st time (deterministic)

56 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Memory capacity limited to 500 nodes in TECNO- Streams synopsis, 500 KNN-instances

57 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Bigger Data Set (~ 30K sessions): Drastic Changes: F1 versus session number (vertical lines: environment changes) Ramp-up: both deteriorate equally as environment changes Either one of KNN or TECNO-Streams seem to perform better depending on profile

58 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Bigger Data Set (~ 30K sessions): Mild Changes: F1 versus session number KNN-Streams slightly higher ? But overall both are poor Possibly because of extremely high dimensionality (>17000) and sparsity! which wrecks havoc on Collaborative filtering in streaming environments!!!

59 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Bigger Data Set (~ 30K sessions): Repeating Drastic Changes: F1 versus session number (vertical lines: environment changes) Either one of KNN or TECNO-Streams seem to perform better depending on profile

60 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Personalization: Implementation Issues Fast Easy Scalable Cheap? Free…? Free…? Web Usage Mining: - Ambiguity: - Implicit Semantics: - Explicit Semantics: - What is effect of generalization / URL compression? - Noise: Effect of post- processing: - Robust profiles - Frequency averaging - Detecting and characterizing evolution in dynamic environments - Recommender Systems in dynamic environments - Recommender Implementation - Mining Conceptual Web Clickstreams

61 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Summary of Methodology Systematic framework for a fast and easy implementation and deployment of a recommendation system on one or several affiliated or subject- specific websites based on any available combination of open source tools that include –crawling, –indexing, and –searching capabilities

62 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Supported Approaches Content based filtering (straight forward) Collaborative filtering (more complex) Hybrids that combine the power of both (2 types): –Cascaded (2 options): First collaborative filtering (obtain collaborative recommendations), then content-based filtering (on previous result) First content-based filtering (obtain content-based set of recommendations), then collaborative filtering (on previous result) –Parallel/combined: Perform collaborative filtering on original input Perform content-based filtering on original input Then combine resulting recommendations above by weighting, etc.

63 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments What for? Easily "implement" (existing) recommendation strategies by using a search engine software when it is available, Benefit to research and real life applications –by taking advantage of search engines' scalable and built-in indexing and query matching features, – instead of implementing a strategy from scratch.

64 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Advantages to Expect… Multi-Website Integration by Dynamic Linking: –dynamic, personalized, and automated linking of partnering or affiliate websites –Crawl several websites + connect through common proxy Giving Control Back to the User or Community instead of the website/business –no need for intervention from websites The Open Source Edge Tapping into IR Legacy

65 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Search Engine 1) Crawling: A crawler retrieves the web pages that are to be included in a searchable collection, 2) Parsing: The crawled documents are parsed to extract the terms that they contain, 3) Indexing: An inverted index is typically built that maps each parsed term to a set of pages where the term is contained, 4) Query matching: –Submit input queries in the form of a set of terms to a search engine interface or to a query matching module –that compares this query against the existing index, –to produce a ranked list of results or web pages. Two open source products that enable a fast and free implementation of Web search, –Text search engine library: Lucene, –Web search engine: Nutch, built on Lucene

66 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Lucene D. Cutting and J. Pedersen, Space optimizations for total ranking, RIAO (Computer Assisted IR) 1997 http://lucene.apache.org/ high-performance, full-featured text search engine library written in Java, can support any application that requires full-text search, especially cross-platform. Examples of using Lucene: Inktomi and Wikipedia's search feature powerful features through a simple API, include –scalable, high-performance indexing, available as Open Source software under the Apache License

67 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Lucenes features ranked searching various query types: phrase, wildcard, proximity, fuzzy, range, and more fielded searching (e.g., title, author, contents), date-range searching, sorting by any field, multiple-index searching with merged results, allowing simultaneous update and searching All the above Heaven on Earth! for implementing recommender system

68 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Nutch http://lucene.apache.org/nutch/: Lucene based Web searchhttp://lucene.apache.org/nutch/ Adds Web specifics to Lucene: crawler, link-graph database, parsers for HTML and other document formats (pdf, ppt, doc, plain text, etc). Document = sequence of Fields. –Field values may be stored, indexed, analyzed (to convert to tokens), or vectored. Uses Lucene's index: Inverted Index that maps a term field ID, and a set of document IDs, with the position within each document. Given a query, Nutch by default searches URLs, anchors, and content of documents

69 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Proposed Methodology Two requirements for tweaking a search engine to work like a recommender sys. 1.An index: The source of the recommendations must be indexed in a format that is easy to search. 2.A querying mechanism: –the input to the recommendation procedure must be transformable into a query –Query is expressed in terms of the entities upon which the index is based

70 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Content-based filtering Given a few pages that a user has viewed, the system recommends other pages with content that is similar to the content of the viewed pages Step 1: Preliminary Crawling and Indexing of website(s) (done offline): to form content of the recommendations, and then forming a reverse index that maps each keyword to a set of pages in which it is contained. Store the most frequent terms in each document as a vector field, that is indexed and used later in retrieval Step 2: Query Formation and Scoring: transform a new user session into a query that can be submitted to the search engine. Map each URL in user session to a set of content terms (top k frequent terms) using an added package net.nutch.searcher.pageurl. Combine these terms with their frequencies to form a query vector, Submit query to Nutch as a Fielded query (i.e. the query vector is compared to the indexed Web document vector field). Finally, rank results according to cosine similarity with the query vector in the vector space domain modification of the default scoring mechanism of SortComparatorSource in the LuceneQueryOptimizer class (which is part of the package net.nutch.searcher) session URLS terms fielded query vector results (ranked according to cosine similarity (result vector, query vector))

71 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Cascaded Hybrids Recommendations (items) Previous sessionsInfo 2 Collaborative filtering Content-based filtering Type 1: compares current session to (all) previous sessions Collaborative session Recommendations (items) User profilesInfo 2 Collaborative filtering Content-based filtering Type 2: compares current session to several user profiles Collaborative session

72 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Implementation Crawled web pages in following domains: –.wikipedia.org –.ucar.edu –.nasa.gov (this corresponds to Step 1 of content-based filtering) The content was indexed using nutch the nutch search engine application was launched to accept queries (in our case transformed user sessions!) A proxy was set at one port on our server based on the Open Source SQUID Web proxy software (http://www.squid-cache.org/) Additional C code to track each session, convert it to an appropriate query, and submit this query to nutch

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81 Conceptual User Session Modeling (w/ lead author: Dr. Hyoil Han, Drexel Univ.) Web Usage Mining: - Ambiguity: - Implicit Semantics: - Explicit Semantics: - What is effect of generalization / URL compression? - Noise: Effect of post- processing: - Robust profiles - Frequency averaging - Detecting and characterizing evolution in dynamic environments - Recommender Systems in dynamic environments - Recommender Implementation - Mining Conceptual Web Clickstreams P. Achananuparp, H. Han, O. Nasraoui and R. Johnson, Semantically Enhanced User Modeling, ACM SAC 2007, also in Tech. report No IST TR-06-1, Drexel University, September 2006.

82 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Windows to the Universe: http://www.windows.ucar.edu (education & outreach website for NASA, NCAR, and other research agencies/groups)http://www.windows.ucar.edu P. Achananuparp, H. Han, O. Nasraoui and R. Johnson, Semantically Enhanced User Modeling, ACM SAC 2007.

83 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Use Wikipedia categories to get large set of Concept terms (specific to physics, astronomy, earth science, etc) Aberration Accretion Albedo Altitude Andromeda Antimatter Aphelion Apogee Apoapsis Aquatic Mammal Asteroid Astrobiology Astrometry Astronaut Astronomer Astronomy Astrophysics Atmosphere Aurora Big Bang Biosphere Black hole Blizzard Bursters Cenozoic Ceres Chemical Element Chinese Deity Chromosphere Coma Comet Constellation Corona Coronagraph Craters Crustacean Cryosphere Culmination Dark Matter Desert Diety Doppler Effect Doppler Shift Earth Earth's crust Eclipse Ecology Ecosystem Epoch Equinox Eruption Evolution Facula Filament Fireball Flare Forecast

84 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Use URLs to prune Wikipedia concepts to those that are relevant to user sessions context (in the usage logs) Accretion Astronaut Atmosphere Aurora Biosphere Black hole Crustacean Culmination Earth Eclipse Epoch Eruption Fossil Fusion Geosphere Granulation Halo Heliosphere Ionosphere Island Jupiter Light Lithosphere Mars Mercury Mineral Moon Occultation Phase Planet Polarization Rain Forest Satellite Scientist Star Weather Zodiac

85 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Map user sessions term sets (content), concept sessions Find most semantically related concept for each term –either the exactly matched concept –or a more general concept. Use the concept hierarchy in WordNets taxonomy –calculate a path-based measure between term- concept pairs –IF Sim < threshold Then unrelated Evaluation: Compare automatically extracted concepts in 100 sessions with those assigned by Human evaluator (ground truth) using prevision/recall P. Achananuparp, H. Han, O. Nasraoui and R. Johnson, Semantically Enhanced User Modeling, ACM SAC 2007.

86 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Summary of Talk: Challenges & Proposed Solutions in Web Usage Mining & Personalization Mining Web Clickstreams User Profiles / User Models –Semantics for disambiguation: Implicitly derived (e.g. from website hierarchy) Explicit (e.g. from related Databases that describe a hierarchy of the items/web pages) Content semantics Conceptual user model Noise Robust profiles –Scalability: how to scale to massive data streams? need to process data in one pass to mine continuously evolving user profiles + work under very stringent constraints –Evolution: Track profiles over periods, Define profile evolution events Recommender Systems (that use the user profiles/models discovered above) –Evolution: Validate continuously mined evolving user profiles against evolution scenarios? –Implementation: fast, easy, scalable, cheap, free (use existing open source indexing+ search engine software)

87 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments REFERENCES IN WEB USAGE MINING & PERSONALIZATION

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97 Nasraoui: Web Usage Mining & Personalization in Noisy, Dynamic, and Ambiguous Environments Thank You! Any questions?


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